The improvements in standards of living and desire for cultural needs have been motivated to various leisure and sports. Most of all, land sports definitely catch popularity. For example, there are various popularized athletic sports, fitness, cycling, and hiking because the land sports have good accessibility and safety, as well as, equipment for the land sports may be easily equipped. Also, water sports are in the limelight. However, the water sports are limited in accessibility and safety, and equipment for the water sports is expensive and difficult in handling, and thus the water sports have not been widely enjoyed in comparison to the land sports.
For example, in case of rafting that uses an inflatable rubber boat to shoot down a rapid stream, since there are few valleys, only some enthusiasts enjoy the rafting. Also, in case of water-ski or yacht, equipment for the water-ski or yacht is expensive, and thus it has low accessibility. Also, ordinary people may not enjoy the water-ski or yacht with their families due to safety problem.